The crystal-blocking lifetime technique (BLT) was used to examine several effects in the in-elastic scattering through 90° of ≈ 5 MeV protons from ≈ 1.5 μm thick germanium crystals to various excited states, using the elastic scattering observed simultaneously as a “promptness” monitor: (a) the enhancement effect an isobaric analog resonance has on the underlying fine-structure states in its vicinity; (b) the effect of different level densities and hence level widths at different excitation energies in different Ge isotopes; (c) the effect on the mean lifetime of the final-state spin in the same isotope; and (d) a slight difference in the mean lifetimes for two different proton groups in the same isotope leading to states of the same spin, a result revealing a possible nuclear (intermediate) structure effect, i.e. one that cannot be explained on the basis of the statistical model. The excitation energies reached in the compound nuclei of arsenic range between 10 and 12 MeV. All results were obtained below the respective lowest neutron thresholds; the resulting lifetimes lie in the range 10−16–10−17 sec, corresponding to mean level widths around 20 eV; this is still considerably less than the estimated mean level spacing, even when the fine structure is enhanced within the analog resonance; i.e. Γ/D ⪡ 1. The actual contact between experiment and calculations based on computer simulations of charged-particle penetration through crystal lattices is made at the level of comparisons of the depths of characteristic blocking dips.

In an investigation of the elastic and inelastic scattering of protons on separated isotopes of 70Ge and 72Ge for the purpose of locating isobaric analogue states of 71Ge and 73Ge in 71As and 73As, respectively, we found one ℓ=0 resonance in each isotope, displaying pronounced structure within their “widths”. The purpose of this Contribution is to present evidence that this structure is intermediate between the gross analogue resonance structure on the one hand, and the ultimate compound-nucleus fine structure on the other hand. It will also be argued that these structures are not Ericson fluctuations.